1. Field of the Invention
The present invention relate to a liquid crystal display device used for a personal computer, a work station, or the like, and particularly to a technique effective in reduction in picture frame width of a liquid crystal display device, and in reduction in thickness thereof.
2. Description of the Related Art
An STN (Super Twisted Nematic) system or a TFT (Thin Film Transistor) liquid crystal display module is widely used as a display device of a notebook-size personal computer or the like.
The liquid crystal display module is constituted by a liquid crystal display panel in which a driving circuit portion is arranged at its periphery and a backlight unit for illuminating the liquid crystal display panel.
The backlight unit is constituted by, for example, a light guide body for guiding light radiated from a light source to a portion distant from the light source and for uniformly irradiating the whole liquid crystal display panel with the light, a cold-cathode fluorescent lamp as a linear light source arranged in the vicinity of the light guide body, along a side of the light guide body, and in parallel with the side, a diffusion sheet arranged on the light guide body, a lens sheet (also called a prism sheet) arranged on the diffusion sheet, and a reflection sheet arranged to extend to a lower side of the light guide body, which are housed in a mold.
Incidentally, the technique like this is disclosed in, for example, Japanese Patent Publication No. 19474/1985, Japanese Utility Model Unexamined Publication No. 22780/1992, and U.S. Pat. No. 5,835,139.
FIG. 22 is a schematic view for explaining an example of a fitting method for fitting a liquid crystal display module to a notebook-size personal computer.
In the drawing, reference numeral 100 designates an outer case of a display portion of a notebook-size personal computer; and 101, an inner case of the display portion of the notebook-size personal computer. As shown in the drawing, a liquid crystal display module 102 is fixed to the outer case 100 of the notebook-size personal computer by fitting screws 120 through a side beam 110.
Thus, inserts to which the fitting screws 120 are screwed, are embedded in the mold of the liquid crystal display module 102.
Incidentally, although the side beam 110 and the fitting screws 120 are provided at both sides of the liquid crystal display module 102, they are omitted in FIG. 22.
However, in recent years, as a picture frame width of the liquid crystal display module is reduced and the thickness thereof is reduced, the thickness of the mold itself is further reduced to, for example, 5.0 mm or less. xe2x80x9cThe picture framexe2x80x9d of the liquid crystal display module described in this present specification designates, for example, a frame-like portion surrounding an opening both of which are provided in an upper surface of the liquid crystal display module 102 shown in FIG. 22.
Thus, in a conventional liquid crystal display module, there has been a problem that it is difficult to certainly fit the insert in the mold.
Besides, there is also known a method in which a compromise plate nut is used, and the fitting screw 120 is screwed to this compromise plate nut, so that the liquid crystal display module is fitted to the notebook-size personal computer.
In this case, the fitting screw 120 is prevented from being dropped off from the frame by inserting the compromise plate nut into a notch of the mold (the inner case) and pressing it with a side of the frame (an outer case) which is fitted in this so as to cover the outer periphery of the mold.
However, there has been a problem that it is difficult to simultaneously fit four or more compromise plate nuts in the notches of the mold and to cover them with the frame.
The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide a technique in a liquid crystal display device which enables a screw member to which a fitting screw for fixing a liquid crystal display device to an exterior case is screwed, to be easily and certainly fitted.
Another object of the present invention is to provide a technique in a liquid crystal display device which enables a screw mechanism of a fitting screw for fixing a liquid crystal display device to an exterior case to be simplified.
Still another object of the present invention is to provide a technique which enables the picture frame width of a liquid crystal display device to be reduced.
Still another object of the present invention is to provide a technique which enables the thickness of a liquid crystal display device to be reduced.
The objects, other objects and novel features of the present invention will be clarified by the description of the present specification and the accompanying drawings.
Among the inventions disclosed in the present application, the brief descriptions of the typical ones are as follows:
That is, the present invention is applied to a liquid crystal display device in which a frame member (casing-like member) is fixed in a housing member (typified by a member known as a mold) for housing components (liquid crystal display panel, light source, optical sheet, etc.) of the liquid crystal display device to constitute a so-called liquid crystal display module, and this liquid crystal display module is fixed to an exterior case.
The housing member includes, for example, a main surface and side surfaces formed around its periphery, and optical parts as the components of the liquid crystal display device are housed on the main surface surrounded by the side surfaces.
In the case of the liquid crystal display module provided with a sidelight type light source, a reflection plate, a light guide body, an optical sheet such as a light diffusion sheet and a prism sheet are stacked up in this order on the main surface. The light guide body is arranged in the inside of the housing member so that one of its main surfaces faces the main surface of the housing member, and a light source unit including a fluorescent lamp is provided along at least one of its side surfaces.
In the case of the liquid crystal display module provided with a direct backlight type light source, a reflection plate, a light source unit made of a plurality of fluorescent lamps fixed to this, a light diffusion plate, an optical sheet, and a liquid crystal display panel are stacked up in this order on the main surface.
Either of the light sources is arranged to face a main surface of the liquid crystal display panel opposite to a display surface side (main surface side of a frame member), and irradiates light (illuminating light) radiated from this light source to the main surface of the liquid crystal display panel. Incidentally, this stacking direction of the parts is called a thickness direction of the liquid crystal display device or the liquid crystal display module in the present specification.
The liquid crystal display panel is also called a liquid crystal display element, and is distinguished from the liquid crystal display device including this and its peripheral part. The exterior case is a box in which the liquid crystal display module (also called the liquid crystal display device) including the housing member and the frame member is housed, and corresponds to, for example, a housing of a notebook-size personal computer. Thus, for example, the outer surface of the liquid crystal display module is covered with the exterior case (also called the outer case) except for its display surface (a screen on which an image is displayed).
When the present invention is applied to this sort of liquid crystal display device, a screw tightening member (hereinafter referred to as a xe2x80x9cscrew memberxe2x80x9d) to which a fitting screw for fixing the liquid crystal display module to the exterior case is screwed, is provided at the side surface (side wall) of the housing member, a protruded portion protruding in the thickness direction of the liquid crystal display module (in other words, in the height direction of the side wall of the housing member) is provided in a region where the screw member of the housing member is provided, and further, an opening in which the protruded member of the housing member is inserted, is provided in the frame member. In the case of the fitting screw having external thread (i.e. being a bolt), the screw member has internal thread formed thereat (as being i.e. Nut).
The aforementioned means is able to sufficiently increase the thickness (in the thickness direction of the liquid crystal display module) of the periphery of the screw member of the housing member.
For example, even if the thickness (in the thickness direction of the liquid crystal display module) of the housing member is made 5.0 mm or less by the reduction in thickness of the liquid crystal display device, the present invention is still able to prevent the screw member from rotating in the housing member or being drawn out therefrom.
Besides, the present invention is characterized in that in a liquid crystal display device, a screw member to which a fitting screw for fixing the liquid crystal display device to an exterior case is screwed, is provided at a side wall of a housing member, a protruded portion protruding in a direction of a tapped hole of the screw member is provided in a region of the side wall of the housing member where the screw member is provided, and further, an opening in which the protruded portion of the housing member is inserted, is provided in a side wall of a frame member.
The aforementioned means is able to reduce the picture frame width of the liquid crystal display module by the thickness of the frame member.
Besides, the present invention is characterized in that in a liquid crystal display device, a screw member to which a fitting screw for fixing the liquid crystal display device to an exterior case is screwed, is provided at a side wall of a housing member, and a sectional shape of the screw member is made such that a length in a direction orthogonal to the thickness direction of the liquid crystal display device is longer than a length in the thickness direction of the liquid crystal display device.
Since the sectional shape of the screw member is made, for example, elliptical or rectangular, the aforementioned means enables to prevent the screw member from rotating in the frame member or being drawn out therefrom.
Besides, the present invention is characterized in that in a liquid crystal display device, a screw member to which a fitting screw for fixing the liquid crystal display device to an exterior case is screwed, is fixed to a side wall of a housing member by adhesion or mechanical means.
Since the screw member is previously fixed to the side wall of the housing member, the aforementioned means facilitates fitting of the screw member to the housing member, and enables to prevent the screw member from being dropped off from the frame member in an assembling process of the liquid crystal display device.
Besides, the present invention is characterized in that in a liquid crystal display device, a screw member to which a fitting screw for fixing the liquid crystal display device to an exterior case is screwed, is inserted in a groove provided in a side wall of a housing member, and an opening of the groove is covered with a frame member.
Since the screw member is held by the groove provided in the housing member, the aforementioned means facilitates fitting of the screw member to the housing member, and enables to prevent the screw member from being dropped off from the frame member in an assembling process of the liquid crystal display device.
Besides, the present invention is characterized in that in a liquid crystal display device, a screw member to which a fitting screw for fixing the liquid crystal display device to an exterior case is screwed, is provided in a concave portion provided in a side wall of a housing member, and is held by a side wall of a frame member and a pawl provided on the side wall of the frame member.
Since the screw member is held by the concave portion provided in the housing member, the side wall of the frame member, and the pawl provided on the side wall of the frame member, the aforementioned means facilitates fitting of the screw member to the housing member, and enables to prevent the screw member from being dropped off from the frame member in an assembling process of the liquid crystal display device.
Besides, the present invention is characterized in that in a liquid crystal display device, a fitting screw for fixing the liquid crystal display device to an exterior case is screwed to a tapped hole provided in a side wall of a frame member.
The aforementioned means enables to simplify a screw mechanism of the fitting screw.
Besides, the present invention is characterized in that in a liquid crystal display device, a fitting screw for fixing the liquid crystal display device to an exterior case, is screwed to a screw member with a spring provided on a frame member.
The aforementioned means facilitates fitting of the screw member to the frame member, and enables to prevent the screw member from being dropped off from the frame member in an assembling process of the liquid crystal display device.
In the case where the liquid crystal display device of the present invention described above is mounted on the housing of a computer, it becomes unnecessary to provide a tapped hole which receives a screw (the aforementioned fitting screw) for fixing the liquid crystal display device to the housing, to the housing member itself. Thus, when the liquid crystal display device (this is already assembled) is mounted on the computer, a mechanical load (vibration, etc.) by rotation of the fitting screw is not directly applied to the housing member. Accordingly, the deformation of the housing member in an assembling process of the computer, and the possibility of the resultant deviation of the liquid crystal display element, the optical sheet, and the like in the liquid crystal display device from the predetermined arrangement can be suppressed. Especially, in the case where the housing member is manufactured as a mold made of a synthetic resin, the effect of preventing the damage of the liquid crystal display device according to the present invention becomes remarkable.
On the other hand, as the liquid crystal display device becomes thinner, the size of the housing member in the thickness direction of the liquid crystal display device also becomes small. Under such circumstances, it becomes difficult to provide the tapped hole to which the fitting screw is screwed, in the side wall of the housing member. If the diameter of the tapped hole is made larger than a predetermined ratio (depending on the material of the housing member) with respect to the height of the side wall of the housing member, the mechanical strength of the tapped hole itself is lowered. Especially, since the screw for fitting the liquid crystal display device to the computer is required to be stronger than the screw used for assembling the liquid crystal display device, its diameter must be made large. On the other hand, in the liquid crystal display device of the present invention, since the tapped hole is not directly formed in the housing member, but is formed in the screw member prepared differently from this or in the side surface of the frame member (especially made of metal), even if the housing member becomes thin, the fixing strength between the liquid crystal display device and the exterior case (housing of the computer, etc.) does not deteriorate. Besides, by providing an opening without screw thread in the side wall of the housing member and by merely inserting the tip of the fitting screw into this, the position of the liquid crystal display device with respect to the exterior case can be further stably held.
Besides, the present invention is characterized in that in a liquid crystal display device in which a driving circuit board is arranged between a liquid crystal display element and a housing member, a concave portion is provided in a region of the driving circuit substrate where a fitting screw for fixing the liquid crystal display device to an exterior case is provided.
Besides, the present invention is characterized in that in a liquid crystal display device in which a driving circuit board is arranged between a liquid crystal display element and a housing member, a region of the driving circuit board where a fitting screw for fixing the liquid crystal display device to an exterior case is provided, is constituted by a flexible wiring board.
According to the aforementioned means, in the case where the driving circuit board is arranged between the liquid crystal display element and the housing member and the thickness of the liquid crystal display module is reduced, interference between the fitting screw and the driving circuit board can be prevented.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings.